The present invention relates generally to the screen stenciling of a pattern on an underlying substrate, such as a glass sheet for example, and, more particularly, to a support for the screen employed in such a stenciling operation.
One of the most common expedients for applying patterns or designs on glass sheets for use in specific applications, such as for glazing closures in automobiles and the like, is the well-known "silk screen" stenciling or printing technique. Generally, the glass sheets are individually positioned beneath an elevated screen assembly which is then lowered onto the glass sheet. The printing material is then forced, as by a squeegee for example, through the perforated area constituting the pattern in the screen onto the glass sheet to form the desired pattern thereon. The screen is then lifted off the glass sheet to allow replacement of the printed sheet with a fresh sheet.
Usually, the printed design, which may be in the form of indicia, bands, stripes or the like, is applied interiorly of the marginal edges of the glass sheets and conventional coating or silk screen printing machines have satisfactorily performed this function. However, recent automotive styling features require the application of a band of coating material of predetermined width along the entire marginal edge of such sheets, the outer peripheral edge of the band extending right up to the marginal edge of the sheet. This has posed problems in conventional screen stenciling apparatus because the perforated pattern of the screen must extend slightly past the marginal edge of the sheet in order to ensure the application of coating material right up to such edge. As a result, the squeegee force, during its traverse across the pattern at such edge, stretches and/or bends the pattern portion thereover. This repeated action prematurely weakens and often tears the pattern portion of the screen, requiring frequent, costly screen replacement and consequent loss of production to effect such replacement.